1. Field of the Invention
The present invention relates to a copying apparatus and particularly to an improvement of an automatic resetting mechanism of a copying apparatus capable of setting selectively a duplex copy mode or a composite copy mode.
2. Description of the Prior Art
There has been proposed a copying apparatus capable of selecting a duplex copy mode or a composite copy mode to copy two original images on both faces or one face of a sheet of copy paper.
Such a copying apparatus has a mechanism called an intermediate tray unit so that a sheet of copy paper on which a first copy operation has been completed is temporarily stored in the intermediate tray unit and is fed therefrom for a second copy operation.
On the other hand, a copying apparatus using an automatic resetting mechanism has been proposed. This automatic resetting mechanism resets various modes to a standard mode (with conditions of a copying magnification being an equal scale, the number of copies being one, and a density being medium for example) if any key is not operated within a prescribed period of time after an end of a copy operation or after input by a mode setting key.
Generally, in a duplex (or composite) copy mode, a first document and a second document are used. First, an image of the first document is printed on a first face (or an area of the first face) of a sheet and then an image of the second document is printed on a second face (or the remaining area of the first face) of the sheet. Thus, it is necessary to change the first document for the second document during operation in the duplex (or composite) copy mode.
However, it sometimes happens that the set mode including the duplex copy mode (or the composite copy mode) returns to the standard mode because of a lapse of an automatic resetting period before setting of the second document after the copy operation of the first document. In such a case, it is necessary to set again the desired mode, which is troublesome. If copy operation is started without setting again the desired mode, copy is made in a wrong manner.
Under such circumstances, several proposals has been made. The U.S. Pat. No. 4,054,380 discloses a copying apparatus in which all the copy conditions are cleared if it is not operated within a predetermined period of time.
The U.S. Pat. No. 4,222,660 discloses a copying apparatus in which an operation mode is set to an initial mode at the time of turning on the power supply, or at the time when the subsequent operation is not started within a prescribed period of time after an end of copy operation, or at the time when the subsequent operation is not started within a prescribed period of time after input through key operation.
The U.S. Pat. No. 4,123,155 discloses a copying apparatus having a function of discharging sheets of copy paper existing in an intermediate tray without printing those sheets.
In addition, the U.S. Pat. No. 4,017,170 discloses a copying apparatus in which aftertreatment is applied to a photoconductive drum to cause the surface potential thereof to be uniform after completion of a copying process by rotating the photoconductive drum.